Its not poor wording in the NOTAM, it explicitly states to do so. From the first page:
(A0289/15 NOTAMN
Q) EHAA/QSUXX/IV/NBO/E /245/999/5259N00454E999
A) EHAA B) 1503230000 C) 1504122359
E)A STANDBY CAMPAIGN AT MAASTRICHT UAC IS CONDUCTED IN ORDER TO REDUCE THE FREQUENCY LOAD AND THE NUMBER OF CROSS-TRANSMISSIONS. THE PHRASEOLOGY 'STANDBY FOR MAASTRICHT ON (CHANNEL-NAME)' CAN BE EXPECTED FOR TRANSFER OF FREQUENCY. PILOTS ARE REMINDED TO ANNOUNCE THEY ARE STANDING BY WHEN FREQUENCY TIME ALLOWS.